Cross-Layer Optimal Joint Packet Routing and Blocklength Design for Latency-Sensitive Wireless Communication

IEEE Transactions on Wireless Communications, vol. 25, pp. 16874–16887

Abstract

In this paper, we consider a latency-sensitive wireless network and aim at minimizing the overall transmission latency via an optimal cross-layer design. In particular, we assume a packet divided into multiple subpackets is supposed to be routed from a source node to a destination node through a wirelessly connected multi-device network. Each activated routing link is assigned a dedicated subcarrier, allowing simultaneous transmission and reception. Taking into account the routing ability at the network layer and the finite blocklength (FBL) effects at the physical layer, via an error propagation method, we first derive out the average transmission latency for completing a data forwarding task under buffer limit at each routing device, while retransmissions are scheduled against transmission failures. Afterwards, we formulate an average transmission latency minimization problem via jointly optimizing the routing path at the network layer and the blocklength allocation at the physical layer. To optimally address the cross-layer mixed-integer nonlinear problem, we characterize the optimal blocklength design for given routing path as an equation system, which is efficiently solved via iterative fixpoint checks. The performed characterization enables a filtering criterion for efficiently evaluating the performance bound of any routing path with respect to a threshold, based on which we propose an efficient algorithm for the optimal routing path filtering, together with a low-complexity iterative routing algorithm for suboptimal routing design. The global optimal joint solution is obtained as the filtered optimal path, combined with the correspondingly optimized blocklength solution. Finally, we numerically validate the effectiveness and optimality of our proposed solution, as well as the necessity of cross-layer design for latency minimization.

Authors 4

1. Xiaopeng Yuan Aachen Chair of Information Theory and Data Analytics

   RWTH Aachen University

   Affiliation as printed

   Chair of Information Theory and Data Analytics, RWTH Aachen University, Aachen, Germany

2. Boyao Li Aachen Chair of Information Theory and Data Analytics

   RWTH Aachen University

   Affiliation as printed

   Chair of Information Theory and Data Analytics, RWTH Aachen University, Aachen, Germany

3. Yulin Hu

   Wuhan University

   Affiliation as printed

   School of Electronic Information, Wuhan University, Wuhan, China

4. Anke Schmeink Aachen Chair of Information Theory and Data Analytics

   RWTH Aachen University

   Affiliation as printed

   Chair of Information Theory and Data Analytics, RWTH Aachen University, Aachen, Germany